Study, Based On The Structure Of Chinese Characters, Chinese Text Watermarking Technology

Recently, with the rapid development of computer multi-media and network technology, more and more document products(books, contracts, documents, notes, etc.) use digital forms to preserve and transmit, more attention is being paid to the document watermarking which is used to ensure the products' safety, authenticity and reliability.According to the concept of "flappable" pixels , this paper confirms 16 3×3 best "flappable" patterns of binary text image(16 patterns for short); according to the two evaluation criterion of binary image: distortion and DRDM, confirms 8 3×3 best vision effect patterns after flip in the 16 patterns(8 patterns for short). The structural characteristics of Chinese characters is studied through experiments and we find that Chinese characters contain a large number of 16 patterns and 8 patterns, and much more symmetrical than that of English letters. Two document watermarking algorithms proposed in this paper are based onabove conclusions.The first watermarking algorithm chooses watermarking's embedded pixels by locating the position of 16 patterns in the document image , uses a key to enhance the randomness and security of the embedded pixels, embeds watermarking through flipping the central pixel of the patterns. The experiments prove that the algorithm has high capacity and low visual distortion. At the same time it can resist Gaussian noise, salt and pepper noise attack and compression operations, and can also resist smearing, distorting, shearing and other malicious attacks to some extent, thus shows stronger robustness.The second watermarking algorithm divides the image into blocks, and extracts authentication summary through the relationship between the 8 patterns and 16 patterns of each block, embeds the summary in the image after scrambling. Experiments prove that the algorithm can extract the hiding data without using the original image, it has good vision quality and can achieve location the tamper, and can be used in the content authentication of Chinese contracts and documents.